This invention relates to an apparatus for moistening the gummed closure flaps of envelopes, and more particularly to a moistening apparatus and associated liquid reservoir assembly for use in a mail handling machine.
Mail handling machines, such as that described in U.S. Pat. No. 4,935,078, process mixed mailpieces (varying size) in a high speed manner. These known mail handling machines typically include a front end feeder, a singulator, a moistener, a sealer, and a printing device. The front end feeder shingles the incoming mailpieces (such as envelopes) and the singulator grabs the bottom envelope from the shingled stack of envelopes for subsequent processing downstream. Upon passing by the singulator, the envelope is successively fed past the moistener where its flap portion is moistened and is then passed through a sealer where the flap is sealed prior to the printing of, for example, postage values thereon by the printing device (postage meter). Moreover, the mail handling machine may further include a scale for weighing the mailpieces and a tape mechanism for the printing of indicia on a tape.
There are a number of conventional moistening devices that are used in mail handling machines for moistening the gummed portions of envelope flaps passing thereby. These moistening devices either apply liquid to the gummed portion by direct contact therewith or spray liquid onto the gummed portion without physical contact between the envelope flap and the moistening device. Each of the contact and non-contact moistening devices have certain operational limitations. For example, contact moisteners such as wicks or pads typically receive liquid from a liquid reservoir via capillary action and transfer that liquid onto the flap gummed portion by direct contact therewith. The gummed portion is activated to become sticky for subsequent sealing due to the application of the liquid and the rubbing action between the flap and pad. However, it is inevitable in such moistening devices that the pad or wick will have a certain amount of the gummed portion transferred onto its surface. The build up of the gummy material on the pad, over time, eventually impacts the ability of the pad to apply the appropriate amount of liquid onto the envelope flap resulting in insufficient or spotty activation of the gummed portion of the envelope; which in turn leads to an unsealed or improperly sealed envelope.
U.S. Pat. No. 4,873,941 describes a non-contact moistening device which overcomes the problems associated with the contact systems set forth above by spraying liquid onto the gummed portion of the envelope flap. However, this device requires a complicated and expensive control mechanism to ensure that only the gummed portion receives the sprayed liquid to prevent damage to the envelope contents due to inadvertent contact with the sprayed liquid. Furthermore, since there is no contact between the spraying device and the gummed portion, the activation of the gummed portion is not assisted by any rubbing action, and therefore increased amounts of liquid (as compared to contact systems) need to be sprayed onto the gummed portion in order to ensure its activation. The excess sprayed liquid presents a problem in that it runs off the envelope flap and must somehow be collected and recirculated within the mail handling machine. Additionally, the excess liquid further exacerbates the problem of preventing damage to the envelope contents.
U.S. Pat. No. 3,948,216 issued to Reid et al. on Apr. 6, 1976 and incorporated herein by reference, to a large extent overcomes the above-mentioned problems of the prior art devices by utilizing a moveable endless belt in communication with a liquid reservoir to moisten the gummed portion of envelope flaps. The endless belt is continuously rotated through the liquid reservoir such that a portion of its surface is always presented for contact with the passing envelope flap. Since the endless belt is constantly moved through the liquid reservoir, the tendency for it to become gummed up is greatly reduced. Moreover, since the endless belt presents a much greater surface area for use in transferring liquid to the gummed portion, even if some of the gummed portion is transferred to the endless belt, a build up of the gummy substance on the belt which would require replacement of the belt does not occur as frequently as in the aforementioned contact devices. However, in the event that the endless belt requires replacement for any number of reasons, its replacement is not easily accomplished. That is, since the support structure for the endless belt is connected to the bottom of the mailing machine deck, it is not readily accessible. Therefore, a serviceman is often required to replace the belt which results in service costs in addition to the cost of the belt, as well as increased downtime of the mail handling machine.
Thus, what is needed is a moistening device which overcomes the problems of the prior art devices and which is very accessible such that replacement thereof can be easily accomplished by the owner or operator of the mail handling machine.